Continuous casting vibrating system



June 4, 1968 YEARLEY ET AL 3,386,494

CONTINUOUS CASTING VIBRATING SYSTEM Filed Feb. 18, 1966 2 Sheets-Sheet 1INVENTORS DOUGLAS C. YFARLEY G HENRI H. AUD

A T TORNEY-S.

United States Patent 3,386,494 CONTINUOUS CASTING VIBRATING SYSTEMDouglas C. Yearley, Westfield, N.J., and Henri H. Audi, Elmhurst, N.Y.,assignors to Phelps Dodge Copper Products Corporation, New York, N.Y., acorporation of Delaware Filed Feb. 18, 1966, Ser. No. 528,533 7 Claims.(Cl. 164-260) or during a portion of the casting period. Sticking of thecast in the semi-solidified state to the mold surfaces is overcome oreliminated by such vibration, which also improves and controls thesurface quality of a casting and its grain structure. The displacementof the components being vibrated are usually of quite limited amplitude,usually not exceeding A inch, with frequencies of several hundred toseveral thousand cycles per minute.

The mode of vibration can be sinusoidal, some nonlinear relation otherthan sinusoidal, and by a periodic impact as by a blow from aspring-loaded trip hammer or the like.

In tube casting, particularly tubes of materials comprising copper andcopper alloys, the-re is need for a wide range of different modes ofvibration in order to ob tain optimum casting qualities and grain size,in additon to avoding o-r overcoming sticking.

The principal objective of the present invention is to provide animproved continuous casting system capable of vibrating in a widevariety of modes and adjustable as to the frequency and amplitude ofeach of its vibration modes.

According to the present invention, a mold is mounted on a firstplatform which is releasably attached to a second platform. Spring meansare positioned between the two platforms and supports the first platformupon the release of the rigid connection. Controllable vibrators areoperatively connected toeach platform. The mold is vibrated in accordwith -a plurality of possible vibrations of the first platform alone, orin combination with the second platform rigidly or resiliently connectedthereto.

These and other features and objects of the invention will be apparentfrom the following description of a preferred embodiment of the presentinvention as illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is the front elevation of a vibrating support for a mold;

FIGURE 2 is a side elevation of the bottom portion of the support asviewed along section line 2-2 of FIG- URE 1;

FIGURE 3 is a sectional plan view as viewed along section 33 of FIGURE 2with certain portions shown in dot and dash lines representing portionslocated above the sectional line; and

FIGURE 4 is a sectional elevation as viewed along sectional line 44 ofFIGURE 2.

In the drawings, like reference characters refer to identical parts.

The vibrating mechanism of this invention is useful in any continuouscasting system where continuous or interrupted relative vibratorymovements are desired between the mold and the casting. Our inventionmay be used in the casting of dense objects, such as rods, or hollowobjects, such as tubes. It gives special advantages for objects ofcopper or copper alloys as their surface and grain size may becontrolled by use of it.

According to the preferred embodiment of the invention we provide aplurality of vibration modes that are controlllable, even during theactual casting of the objects, by relatively simple adjustments.

As shown in FIGURE 1, a mold 12 is supported on a platform system 11.The platform motion 11 is responsive either to one or two vibrators orto both. One of the vibrators, 20, provides a very high frequencysinusoidal vibration and effects vertical vibratory forces on theplatform. Another vibrator, 21, is connectable to the platform system 11and provides low frequency non-sinusoidal vibrations which effect anupstroke or vertical rising of the platform that is different in forceor duration to the downstroke.

A second, auxiliary platform system 10 is releasably connected toplatform system 11 and either rigidly or resiliently support the mold12. Platform system 10 is connected to a third vibrator 25. The mold andvibratoiy apparatus is supported on a rectangular frame formed fromchannel beams 36.

Referring now to the apparatus as illustrated in greater detail inFIGURES 2 and 3, upper platform system 11 is formed by a pair ofelongated rectangular plates 31. Plates 31 are spaced sufliciently apartto provide a space beneath the mold 12 for passage of the bar or tube(not shown) to be cast in the mold. The withdrawal apparatus (not shown)is located beneath the mold 12. The usual apparatus for supplying moltenmetal to the mold 12 (not shown) is located above mold 12. Mold supportplates 31 are welded to the inner pair of cross-bars 38a, perpendicularto plates 31. Cross-bars 38a are welded to a pair of bottom plates 39spaced outwardly from plates 31. A second pair of cross-bars 38 iswelded to the bottom of plates 39. A pair of plates 40 spaced beneathand parallel to plates 39 are welded to the opposite face of bars 38 and38a. Four antifriction ball bearings are provided in apertures in theplates 39 to receive the four posts 14. The four posts 14 arerespectively guided in vertical movement by four L-shaped brackets 16each having an enlarged cylindrical end portion 15 within which are ballbearings or roller bearings for easy axial sliding therein. A similarroller bearing carrier 15a is provided to guide the lower end of rods14, see FIGURE 4. L-brackets 16 are connected to the lower plateassembly 10 by bolts and nuts 17.

The lower plate assembly 10 is formed from a pair of spaced rectangularplates 30 welded to a pair of crossmernber plates 34 which in turn arecarried by pinions 42. Pinions 42 are rocked on a curved pathapproximately vertical by vibrator 25 through a pair of linkages 26 and26a spaced on opposite sides of the channel member 36. The linkage arm26a is oscillated back and forth a few degrees on a curved path by meansof an eccentric cam on vibrator 25. Each of the linkages 26 is at itsend pivotally attached to channel 36 (which is channeled to accommodatethe generally vertical motion of pinions 42) and this converts thevibrator motion into generally vertical motion of the pinions 42. Inorder to effect symmetrical forces generated by the vibrator 25, aconnecting rod 44 connects the pinions assembly on the right with acomparable pinions assembly on the left side of the lower plate assembly10. Rod 44 is pivotally connected by connectors 46 at one end to linkage26 and at the opposite end to a triangular plate 48.

Plate assembly 11 is resiliently supported on the lower plate assembly10 by four springs in opposing pairs, 13A

and 13B. Spring pairs 13B are mounted on a plate 32 which in turn isbolted to plate 30 of the lower platform assembly 10. Spring pairs 13Aare mounted on similar plates 32a which in turn are mounted by bolts tocrossplates 34. The upper end of springs 13B are support to the lowerfaces of plate members 41 of plate assembly 11 and spring pairs 13Asupport plates 40. Platform 11 is displaceable vertically, and, inconjunction with platform 10, horizontally. Two high frequency vibrators20 are attached to the bottoms of support plates 31.

Platforms 11 and are arranged also to be rigidly connected by releasableconnections. Bolts 18 and lower nuts 19 and 19a rigidly connect lowerplate 30 to upper plate 41. When the bolts 18 and nuts 19 and 19:: arein place, as shown, the upper platform assembly 11 is rigidly connectedto the lower platform assembly 10.

As shown in FIGURE 1, a vibrator 21 is connected to the upper platformassembly 11 by means of struts 22. Struts 22 have bolts 50 which may bescrewed into crossmembers 38 to connect platform assembly 11 to thevibrator 21. The vibrator 21 may be actuated by hydraulic means (asshown in FIGURE 1) or by mechanical means (not shown) to generatevertical vibrations at a low frequency, on the order of 100 cycles perminute, with a stroke on the order of 4 inch to 3 inches. When usinghydraulic means, vertical movements of vibrator 21 are detected bypositionable limit switches 23 and adjustable trips 24 for actuatingreversing switches (not shown) to control its stroke length and periodof vibration. Preferably, the speed of movement in one direction isdifferent from the speed of movement in the other direction. In the art,this is known as the vibrator speed ratio. The speed in the upwarddirection in relation to the speed in the downward direction is madeadjustable by means such as a pressure valve (not shown). Thus, vibrator21 develops motions on the upper platform level 11 which arenon-sinusoidal in nature, being effective at rapid upward motion with aslower downward motion. The downward motion is preferably adjusted to beof the same order of linear speed as the linear movement of the castbeing Withdrawn from the mold 12.

There are five modes of vibration to which mold 12 may be subjected withrespect to amplitude and frequency of vibration. There are three sourcesof vibration forces. Vibrator 25 develops a sinusoidal reciprocalvibration by the linkage 26 to effect an approximately verticalvibratory displacement of platform 11. Vibrator 25 is preferablyadjusted to vibrate within the limits of 100 to 2000 cycles per minutewith an amplitude varying between 0.006 to 0.250 inch. The instantaneousdisplacement X, in inches, may be represented according to the followingformula:

X=a sin W 2 where W is the angular speed of the vibrator 25 in radiansper second; a is the stroke in inches; and t is time (seconds).

A pair of vibrators are symmetrically connected to plate 31 to producevibrations on the upper platform only which rests on springs 13A and13B. The vibrators are not in contact with the lower platform assembly10 at any time. The vibrators 20 may be selected from any of the usualhigh frequency vibrators operated by pneumatic or electrical means foreffecting vibrations in the order of 2000 to 6000 cycles per second. Thevibration forces are oriented to the vertical and may be represented bythe following relation:

P:F sin W t (2) where P is the instantaneous force in pounds on theupper platform assembly 11; F is the maximum force that is developed bythe vibrator in pounds; W is the speed of the vibrator in radians persecond; and t is the time in seconds.

The third vibrator 21 has been described above. A mathematicalrelationship to describe its mode of operation is rather complex andprobably indeterminate and is not discussed herein.

The five modes of vibration to which the mold may be subjected inaccordance with our invention are as follows.

First mode of vibration Vibrator 21 is disconnected from the upperplatform 11 by means of the bolts 50 connecting the struts 22 toplatform system 11. Platform systems 11 and 10 are connected together bythe releasable rigid connections of bolts 18 and nuts 19 and 19a.Vibrator 25 is placed in operation (but not vibrators 20) and throughlinkage 26 causes both platforms 10 and 11 to vibrate sinusoidallyaccording to relationship (1) above. The amplitude a or the speed W canbe changed by changing the eccentric cam of vi brator 25 or the speed ofits motor. The vibration of the whole assembly depends upon the rockingaction of pinions 42. Since both platforms 10 or 11 are connected thereis no relatively motion between the posts 14 and the plate assembly 11.

Second mode of vibration Bolts 18 and nuts 1% are disconnected.Vibrators 20 are not operated and vibrator 25 is operated. Springs 13thus serve to provide resilient support between the platforms. Therelationship of instantaneous displacement of this mode of vibration,without considering transient effects, may be represented by thefollowing expression:

Ka sin W t KM(W (3) Where X is the instantaneous amplitude of thedisplacement of platform 11 and, thus mold 12; K is the effective springconstant of the four springs 13 in pounds per inch. Aside from K, thenumerator will be recognized as Formula 1 discussed above. W is afunction of the speed of vibrator 25 as discussed in regard toFormula 1. M is the total mass (in slugs) of the platform assembly 11and mold 12 supported by the four springs 13. According to this mode ofvibration, selection of the spring constant K, platform mass M and speedW, is such that a vibration near the mechanical resonant frequency ofthe system is the preferred vibration frequency. During casting, theamplitude of vibration can be increased or decreased by slight changesin the frequency as by adjustment of the vibrator motor speed. It is tobe noted that this mode of operation also has a self-regulating feature.If a casting tends to hang up or stick in the die, as often occurs, inspite of the utmost precautions, the effective mass M on the upperplatform 11 will increase as a result of the drag. The springs 13 willthen tend to deflect more and follow the casting movement andsimultaneously react to sustain a greater load. Thus, when the castingsticks the system automatically compensates for the sticking by movingwith the casting and simultaneously exerting a higher pull to free thecasting thereby the sticking is overcome, without breakage as wouldresult from the extremely high forces at a sudden stoppage.

Third mode of vibration In this mode of vibration the rigid connection(bolts 18 and nuts 19 and 19a) between the platforms are disconnectedand the vibrator 21 is disconnected. In this mode, platform 11 isoscillated by its vibrator 25 and the high speed vibrator 20 for theupper platform 11 is placed in operation. Simultaneously, under this setof dual vibration operation, a superimposed sinusoidal motion iseffected according to the following relationship:

F sin W t Ka sin W t KM(W2) KM(W where the terms are as defined abovewith the additional factor, W being the speed of the vibrator 20 inradians per second. It will be appreciated that by altering the speed Wof vibrator 25 or the speed W of vibrator 25, the amplitude X and thevibration speed of the upper platform 11 may be altered. It is notedthat the instantaneous displacement, X of the upper platform 11 iscomprised of two vibration components, wherein a high frequencyvibration is, in effect, superimposed on the lower frequency mode ofvibration.

Fourth mode of vibration The connections for this mode of vibration arethe same as that for the third mode, except that the vibrator for thelower platform 25 is not in operation. Accordingly, with only vibrator20 operating, a high frequency vibration is effected whereby asinusoidal vertical reciprocating motion is imparted to platform 11.This effect through the spring action causes an instantaneousdislacement of the mold 12 according to the relationship:

where X, is the instantaneous displacement of the lefthand component ofEquation 4 above. It will be appreciated that an adjustment or a changein the vibration frequency of vibrator 20 effects a change in thefrequency parameter W which, in turn, causes a change in amplitude aswell as frequency of the vibration.

Fifth mode of vibration The rigid connections (bolts 18 and nuts 19 and19a) between platforms 11 and are removed and vibrator 21 is connectedto the upper platform 11 by means of the strut connections 22. Platform11 is sufiiciently raised along posts 14, by raising struts 22 so thatsprings 13 are not contacted during the maximum displacement effected byvibrator 21. Adjustments of limit switches 23, adjustable trips 24 andthe speed ratio varies the length of the stroke, the ratio of the upwardto downward speed of vibration, and the absolute downward speed, asdesired, according to the type of molding or casting that is to beproduced.

Either the first mode of vibration, where vibrator 25 is used, or thefifth mode of vibration, where vibrator 21 is used, may be modified byalso using vibrators 20. The use of vibrators 21 in that manner or inthe third or fourth modes of vibration will give a finer grain structureto castings produced in connection with that use.

We claim:

1. Apparatus for the continuous casting of metals comprising anopen-ended mold, a first platform carrying said mold, a second platformattached to said first platform by a releasable rigid connection, avibrating means for vibrating said second platform at a selectedamplitude and frequency, and spring means for connecting said first andsecond platforms and for vibrating said first platform at a differentamplitude than said second platform when said rigid connection isreleased.

2. The apparatus as defined in claim 1 and also including a secondvibrating means attached to the first platform for vibrating said firstplatform at a selected amplitude and frequency.

3. The apparatus as defined in claim 1 and also including a secondvibrating means releasably connected to the first platform.

4. The apparatus as defined in claim 2 and also including a thirdvibrating means releasably connected to the first platform.

5. The apparatus of claim 1 wherein said vibrating means is adapted tovibrate said second platform in a substantially vertical direction at afrequency in the range of about cycles per minute to about 2000 cyclesper minute and with an amplitude in the range of about 0.006 of an inchto about 0.250 of an inch.

6. The apparatus of claim 2 wherein said second vibrating means isadapted to generate generally vertical vibrations at a frequency in therange of about 2000 to about 6000 cycles per second.

7. The apparatus of claim 3 wherein said second vibrating means isadapted to generate generally vertical vibrations having a frequency ofabout 100 cycles per minute, a stroke in the range of about 4 inch toabout 3 inches and a downward speed slower than their upward speed.

References Cited UNITED STATES PATENTS 3,075,264 1/1963 Wognum 164-832,760,243 8/1956 Kerb l64-83 XR 475,848 5/1892 Critcher 259-91 2,353,4927/1944 OConner 164260 XR 2,763,040 9/1956 Korb 16483 XR 2,815,55112/1957 Hessenberg et a1. 16483 2,775,008 12/1956 Easton et al. 1642603,118,195 1/1964 Gouzou et a1. 16483 3,211,432 10/1965 Van Rossen259--91 3,307,230 3/1967 Goss 164282 XR FOREIGN PATENTS 901,235 1/1954Germany.

I. SPENCER OVERHOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner.

1. APPARATUS FOR THE CONTINUOUS CASTING OF METALS COMPRISING ANOPEN-ENDED MOLD, A FIRST PLATFORM CARRYING SAID MOLD, A SECOND PLATFORMATTACHED TO SAID FIRST PLATFORM BY A RELEASABLE RIGID CONNECTION, AVIBRATING MEANS FOR VIBRATING SAID SECOND PLATFORM AT A SELECTEDAMPLITUDE AND FREQUENCY, AND SPRING MEANS FOR CONNECTING SAID FIRST ANDSECOND PLATFORMS AND FOR VIBRATING SAID FIRST PLATFORM AT A DIFFERENTAMPLITUDE THAN SAID SECOND PLATFORM WHEN SAID RIGID CONNECTION ISRELEASED.